Portable computers are commonly provided with two receiving bays. One bay is configured to receive the battery pack, and the other bay, referred to as the secondary or multi-bay, is for optional accessories such as an optical disc player or floppy disc drive. To operate the portable computer without an external power source, a rechargeable battery can be inserted in the battery receiving bay in the computer. When the battery runs low, the user typically must remove the used battery, and replace it with a charged battery.
Many users of portable computers have found that, under some circumstances, the amount of electricity stored in a standard battery, such as an eight-cell battery, is insufficient. When the battery runs low, computer usage must be interrupted while the spent battery is replaced. One solution to this problem is to increase the capacity of the battery. This, however, means increasing the size and weight of the battery pack or casing. Not only is this undesirable, given the trend towards more compact models, but a larger battery also requires a larger receiving bay. Thus, increasing battery capacity translates into higher costs for manufacturing a different computer housing, together with all the re-designing associated with these modifications. An alternative solution is to use a second battery which can be fitted into the multi-bay. Because, however, the multi-bay is designed for use with various peripheral drives, the size of the multi-bay is different than the battery receiving bay. Consequently, the user would need two batteries of different sizes, which are not interchangeable, to operate the computer with two batteries (one in the battery receiving bay and one in the multi-bay). Alternatively, a completely new housing and hardware design must be made to make the battery receiving bay identical to the multi-bay. Both of these solutions, however, are costly.